Bug 7368: POD doc in VirtualShelves.pm

Only moving/adding some documentation in VirtualShelves.pm.
Related to earlier changes in connection with report 7310.
Adding my own signoff, nothing to test here. Does Koha still work? :)

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Passed-QA-by: Paul Poulain <paul.poulain@biblibre.com>
Signed-off-by: Jared Camins-Esakov <jcamins@cpbibliography.com>

C4/VirtualShelves.pm

@@ -597,16 +597,25 @@ sub ShelvesMax {
     return SHELVES_MASTHEAD_MAX;
 }
 
+=head2 HandleDelBorrower
+
+     HandleDelBorrower($borrower);
+
+When a member is deleted (DelMember in Members.pm), you should call me first.
+This routine deletes/moves lists and entries for the deleted member/borrower.
+You could just delete everything (and lose more than you want), but instead we
+now try to save all public/shared stuff and keep others happy.
+
+=cut
+
 sub HandleDelBorrower {
-#when a member is deleted (DelMember in Members.pm), you should call me first
-#this routine deletes/moves lists and entries for the deleted member/borrower
-#you could just delete everything (and lose more than you want)
-#instead we now try to save all public/shared stuff and keep others happy
     my ($borrower)= @_;
     my $query;
     my $dbh = C4::Context->dbh;
 
     #Delete shares of this borrower (not lists !)
+    #Although this would be done later via the FK cascaded delete, we do it now.
+    #Because it makes the following delete statement on shelves more meaningful.
     $query="DELETE FROM virtualshelfshares WHERE borrowernumber=?";
     $dbh->do($query,undef,($borrower));